1. Field of the Invention
The present invention relates to an image forming apparatus such as a copy machine, a printer or the like which provides at least two developing means.
2. Description of the Prior Art
A copy machine having plural developing units being settable thereinto has been well known. In such a copy machine, each developing unit provides a signal means for identifying a color of toner contained therein and, due to the signal means, each color of toner of respective developing units having been set in the copy machine can be detected. When a desired color is designated upon copying, a developing unit having the desired color of toner is automatically selected to develop an electrostatic latent image of a document formed on a photoconductive drum with the toner of desired color.
In such a multi-color copy machine having plural developing units, the black developing unit, namely the developing unit containing black toner is usually assigned to the standard one to be equipped in each copy machine since the probability in use of the black developing unit is assumed to be high. And the black developing unit is automatically designated in the initial state of the machine just after switching on the main switch or when the machine is automatically reset.
However, the copy machine in which the top priority is given to the black developing unit is not always convenient since there may be such a case that the red developing unit is used more frequently rather than the black developing unit. In fact, the red colored copy is desired rather than the black copy in the field of making leaflets.
If the copy machine wherein the top priority is given to the black developing unit is introduced to an office in which color copies of other than black are desired usually, miss copies will be increased since the black developing unit is usually designated. In such a case, the copy machine having the auto reset mode is rather inconvenient since an operator has to operate to switch the black developing unit to another developing unit of desired color upon copying.